This invention relates to an auxiliary apparatus for an internal combustion engine. More particularly, the invention relates to a motor-generator arranged on the turbine shaft of a supercharger in an internal combustion engine, and to control of the motor-generator.
A vehicle that relies upon an internal combustion engine is equipped with a large number of electrical devices. These include a starting motor, an ignition device, alarms, various lighting equipment such as the vehicle headlights, various indicators and the like. The vehicle is provided with a secondary or storage battery as a power supply for these devices, and with a generator driven by the internal combustion engine for the purpose of charging the battery. Vehicles now come equipped with a number of newly developed electrical devices in addition to the equipment mentioned above. All of these devices result in a great amount of power consumption.
To replenish the power consumed by these devices, the battery is charged by the generator, which is driven by the output of the internal combustion engine. However, since the energy involved is rotational energy applied to the generator from the engine crankshaft by way of a V belt, a portion of the net output of the engine is consumed as electric power by the electrical devices.
Furthermore, a size limitation is placed upon the external dimensions of the generator because of the engine layout, as a result of which the maximum power is limited to about 700 W at 24 V. It is quite probable that this will not be sufficient to cope with the power consumption of the many electrical devices expected to be added to vehicles in the future.
Vehicles now come equipped with a supercharger in which a turbine is driven by utilizing the energy possessed by exhaust gas and the engine cylinders are supercharged with air by means of a compressor operatively associated with the turbine, whereby the fuel is burned more efficiently. However, since the exhaust gas has but little energy when the internal combustion engine is running at low speed, supercharging pressure is low and the filling efficiency is poor. The result is an insufficient increase in output and torque.